This invention relates generally to a conductor rail fishplate.
Increasing demands on overhead contact line systems in terms of safety, reliability, current carrying capacity, short-circuit resistance, and minimal installation height have led to the use of conductor rails holding a contact wire that does not carry a tensile load. Fields of application are tunnels and maintenance workshops for electric motor vehicles since work-hindering contact lines can be swung to the side.
Conductor rails are usually molded in lengths of about 12 meters. Conductor rail systems are assembled from successive conductor rails, which must be connected mechanically and electrically. On one hand, the connection requires mechanical strength, maintenance of positive fit, and also transmission capacity for electrical current, which can reach up to 5000 A in current spikes. The positive fit demands that under the load of its own weight, no bends will occur at the joint of two successive conductor rails.
Deformation-free joints of two conductor rail were previously achieved using two plates at the inside of the crosspieces of the conductor rail. These fishplates must be inserted into the hollow spaces of the conductor rails. Then they are pushed against the crosspieces from the outside with screws. The mechanical and positive-fit strength is achieved through wedge-shaped edges on the fishplates and counter shapes in the interiors of the crosspieces. The electrical transmission of current is realized through linear contact between the fishplates and the crosspieces inside of the profile. The linear contacts are achieved through pressure from the tightening of the screws.
A disadvantage for this known conductor rail joint is that two plates must be inserted, holes must be bored in the crosspiece and the plates, and a corresponding number of screws must be tightened. In practice, 16 holes or even threaded holes are bored in each plate and the threads cut. The known conductor rail joint is thus not assembly-friendly. It is also not practical when a conductor rail section must be replaced, because access to the hollow space on the conductor rail is possible only with a narrow object at the lower clamp opening for the contact wire. The linear, not clearly defined electrical contacts limit current transmission.